The invention relates generally to an offset connection assembly for connecting links of a boom assembly of a work vehicle such as a skid steer loader. More particularly, the invention relates to an improved offset connection assembly that includes specially tapered offset pins for securing the lower links to the boom arms of the loader so that the offset pins correct for a shift in the position of the boom or cutting edge of a loader bucket or other like implement.
In the art of manufacturing work vehicles such as skid steer loaders, tractors, etc., the vehicles are often constructed to have pivoting lift arms or booms attached at a proximal end to the body of the vehicle so that the lift arms or booms may lift or carry a work implement such as a bucket loader. As is conventionally known, the work implement is attached to distal ends of the lift arms or booms that are distant from a proximal end. Typically, each lift arm or boom is constructed from a plurality of members. For example, in a skid steer loader 1 (referred to as a xe2x80x9cSSLxe2x80x9d) as shown in FIG. 1, each boom assembly 3 includes a lifting member or boom arm 5, an upper link member 7, and a lower link member 9. In each boom assembly 3, boom arm 5 is fixed at one end to triangular plate member 10. Link members 7, and 9 are pivotally connected at one end to triangular plate member 10, and pivotally connected at another end to cab 15 of the skid steer loader. A hydraulic boom cylinder (not shown) is disposed beneath each boom arm 5 and is likewise pivotally connected to the triangular member at one end and to the cab 15 at another end.
Lifting member or boom arm 5 is fixed at a proximal end to the triangular plate member 10 and at a distal end to the work implement 11. The upper link member 7 is pivotally connected at a proximal end to the triangular plate member and pivotally connected at a distal end to cab 15 of the SSL 1. The cab 15 provides a space for the operator to sit when operating the SSL 1. The lower link member 9 is pivotally connected at a proximal end to the triangular plate member 10 and at a distal end to the cab 15. Typically, a pivot pin (not shown) forms part of the attachment between the lower link member 9 and the triangular plate member 10.
However, the prior art boom assembly 3 has a drawback in that it is difficult to assemble the SSL 1 so that there is complete symmetry between right and left boom assemblies 3. Quite often, one boom assembly 3 is slightly shorter than the other so that the implement 11 is aligned with the ground G in a skewed manner as is shown in FIG. 1. The asymmetry between right and left boom assemblies 3 results is two effects: boom shift and cutting edge shift. It is noted that the degree of boom shift and cutting edge shift shown in FIG. 1 is exaggerated for the purpose of illustration and is not to be construed as a true visual representation of the degree of asymmetry between right and left boom assemblies.
Each lifting member or boom arm 5 pivots along with its respective triangular plate member 10, and when the boom assembly 3 is not in use the boom arm 5 is pivoted until it rests on a stop (not shown) on the body of the SSL 1. However, because of boom shift, which results from asymmetry between right and left boom assemblies 3, only one boom arm 5 typically rests properly on its respective stop when not in use and the other boom arm 5 either does not engage its respective stop or bounces against it. A problem occurs when both boom arms 5 do not rest properly on respective stops in that one or both boom assemblies 3 suffer unnecessary stress and are placed at risk of damage.
Cutting edge shift is another undesirable result of asymmetric booms. As shown in FIG. 1, the bucket loader work implement 11 has a cutting edge 13. When one boom assembly is longer than the other, the cutting edge 13 is skewed relative to the ground G. For example, as shown in FIG. 1, the left side boom assembly being longer than the right side boom assembly causes the left hand portion of the cutting edge to dip lower (i.e. closer to the ground) than the right hand portion of the cutting edge. In practice, the actual distance that the left hand portion of the cutting edge is closer to the ground than the right hand portion may only be, for example, about one inch. However, even such a small difference affects the quality of digging and/or scooping that can be performed by the bucket loader 11.
Therefore, there is a need for a mechanism for application to a work vehicle 1 that compensates for, or corrects asymmetry between right and left boom assemblies, thereby eliminating or minimizing the deleterious effects of boom shift and/or cutting edge shift.
It is therefore an object of the present invention to provide an improved connection assembly for connecting one of the link members attached to the body of the vehicle, e.g., the lower link member of a boom assembly of a work vehicle, to a triangular plate member of the boom assembly in order to relatively position the lower link member with respect to the triangular plate member so as to correct shift in the boom and to minimize cutting edge shift.
Accordingly, a further object of the present invention is to overcome the disadvantages of the prior art work vehicle boom assemblies by providing the boom assembly with an offset connection assembly for attaching a lower link member to a triangular plate member, wherein the attachment assembly can be assembled to correct shift in the boom and to minimize cutting edge shift.
Another object of the present invention is to provide a mechanism for correcting shift in the boom that is durable and reliable.
A still further object of the present invention is to provide a mechanism for correcting shift in the boom that is simple and cost effective to manufacture and assemble.
In accordance with the above objectives, the present invention provides a boom assembly for attachment to a work vehicle having a body. The assembly includes (a) a boom arm connected at one end to a triangular plate member; (b) a link member, pivotally connected at a first end to the triangular plate member and pivotally connectable at a second end to the body of the vehicle; and (c) an offset connection assembly. The offset connection assembly includes (i) a seat member attached to one of the triangular plate member and the lower link member, the seat member having a first passage formed therethrough, and a seat formed therein, (ii) a hollow offset pin journaled within a hole in the other of the triangular plate and the link member, the offset pin having (a) a surface offset from a center of the pin constructed to engage the seat of the seat member at a selectable orientation, and (b) a second passage formed therethrough, and (iii) a fastener passing through the first and second passages and securely fastening the hollow offset pin and the seat member in the selectable orientation.
In accordance with a still further embodiment, there is provided a work vehicle having right and left boom assemblies, an implement connected to boom assemblies, and a body. Each of the right and left boom assemblies includes (a) a boom arm connected at one end to a triangular plate member, and at another end to the implement; and (b) a link member, pivotally connected at a first end to the triangular plate member and pivotally connectable at a second end to the body of the vehicle. At least one of the boom assemblies further includes (c) an offset connection assembly. The offset connection assembly includes (i) a seat member attached to one of the triangular plate member and the link member, the seat member having a first passage formed therethrough, and a seat formed therein, (ii) a hollow offset pin journaled within a hole in the other of the triangular plate and the link member, the offset pin having (a) a surface offset from a center of the pin constructed to engage the seat of the seat member at a selectable orientation, and (b) a second passage formed therethrough, and (iii) a fastener passing through the first and second passages and securely fastening the hollow offset pin and the seat member in the selectable orientation.
In accordance with a still further embodiment, there is provided a work vehicle having right and left boom assemblies, an implement connected to boom assemblies, and a body. Each of the right and left boom assemblies includes (a) a boom arm connected at one end to a triangular plate member, and at another end to the implement; (b) a lower link member, pivotally connected at a first end to the triangular plate member and pivotally connected at a second end to the body of the vehicle; and (c) an upper link member, pivotally connected at a first end to the triangular plate member and pivotally connected at a second end to the body of the vehicle. At least one of the boom assemblies further includes (d) a connection assembly. The offset connection assembly includes (i) a seat member attached to one of the triangular plate member and the lower link member, the seat member having a first passage formed therethrough, and a seat formed therein, (ii) a hollow offset pin journaled within a hole in the other of the triangular plate and the link member, the offset pin having (a) a surface offset from a center of the pin constructed to engage the seat of the seat member at a selectable orientation, and (b) a second passage formed therethrough, and (iii) a fastener passing through the first and second passages and securely fastening the hollow offset pin and the seat member in the selectable orientation.
In preferred embodiments of the present invention, the surface of the offset pin is a tapered portion, and the seat of the seat member is constructed to engage the tapered portion.
In the work vehicle according to the present invention, each boom assembly preferably comprises an offset connection assembly.
In further preferred embodiments a hydraulic boom cylinder is provided for each boom assembly, pivotally connected at one end to the body of the vehicle and pivotally connected at another end to the triangular plate member.
In accordance with still further, preferred embodiments, the seat member is attached to the triangular plate member and the pin is journaled in the link member.
Further objects, features and advantages of the instant invention will become apparent from the Detailed Description of Preferred Embodiments, which follows, when considered together with the attached drawings.